s390: run user space and KVM guests with modified branch prediction

Define TIF_ISOLATE_BP and TIF_ISOLATE_BP_GUEST and add the necessary
plumbing in entry.S to be able to run user space and KVM guests with
limited branch prediction.

To switch a user space process to limited branch prediction the
s390_isolate_bp() function has to be call, and to run a vCPU of a KVM
guest associated with the current task with limited branch prediction
call s390_isolate_bp_guest().

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Martin Schwidefsky 2018-01-16 07:36:46 +01:00
parent d768bd892f
commit 6b73044b2b
4 changed files with 71 additions and 5 deletions

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@ -378,6 +378,9 @@ extern void memcpy_absolute(void *, void *, size_t);
memcpy_absolute(&(dest), &__tmp, sizeof(__tmp)); \ memcpy_absolute(&(dest), &__tmp, sizeof(__tmp)); \
} while (0) } while (0)
extern int s390_isolate_bp(void);
extern int s390_isolate_bp_guest(void);
#endif /* __ASSEMBLY__ */ #endif /* __ASSEMBLY__ */
#endif /* __ASM_S390_PROCESSOR_H */ #endif /* __ASM_S390_PROCESSOR_H */

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@ -58,6 +58,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
#define TIF_GUARDED_STORAGE 4 /* load guarded storage control block */ #define TIF_GUARDED_STORAGE 4 /* load guarded storage control block */
#define TIF_PATCH_PENDING 5 /* pending live patching update */ #define TIF_PATCH_PENDING 5 /* pending live patching update */
#define TIF_PGSTE 6 /* New mm's will use 4K page tables */ #define TIF_PGSTE 6 /* New mm's will use 4K page tables */
#define TIF_ISOLATE_BP 8 /* Run process with isolated BP */
#define TIF_ISOLATE_BP_GUEST 9 /* Run KVM guests with isolated BP */
#define TIF_31BIT 16 /* 32bit process */ #define TIF_31BIT 16 /* 32bit process */
#define TIF_MEMDIE 17 /* is terminating due to OOM killer */ #define TIF_MEMDIE 17 /* is terminating due to OOM killer */
@ -78,6 +80,8 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
#define _TIF_UPROBE _BITUL(TIF_UPROBE) #define _TIF_UPROBE _BITUL(TIF_UPROBE)
#define _TIF_GUARDED_STORAGE _BITUL(TIF_GUARDED_STORAGE) #define _TIF_GUARDED_STORAGE _BITUL(TIF_GUARDED_STORAGE)
#define _TIF_PATCH_PENDING _BITUL(TIF_PATCH_PENDING) #define _TIF_PATCH_PENDING _BITUL(TIF_PATCH_PENDING)
#define _TIF_ISOLATE_BP _BITUL(TIF_ISOLATE_BP)
#define _TIF_ISOLATE_BP_GUEST _BITUL(TIF_ISOLATE_BP_GUEST)
#define _TIF_31BIT _BITUL(TIF_31BIT) #define _TIF_31BIT _BITUL(TIF_31BIT)
#define _TIF_SINGLE_STEP _BITUL(TIF_SINGLE_STEP) #define _TIF_SINGLE_STEP _BITUL(TIF_SINGLE_STEP)

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@ -107,6 +107,7 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART)
aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
j 3f j 3f
1: UPDATE_VTIME %r14,%r15,\timer 1: UPDATE_VTIME %r14,%r15,\timer
BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
2: lg %r15,__LC_ASYNC_STACK # load async stack 2: lg %r15,__LC_ASYNC_STACK # load async stack
3: la %r11,STACK_FRAME_OVERHEAD(%r15) 3: la %r11,STACK_FRAME_OVERHEAD(%r15)
.endm .endm
@ -187,6 +188,40 @@ _PIF_WORK = (_PIF_PER_TRAP | _PIF_SYSCALL_RESTART)
.popsection .popsection
.endm .endm
.macro BPENTER tif_ptr,tif_mask
.pushsection .altinstr_replacement, "ax"
662: .word 0xc004, 0x0000, 0x0000 # 6 byte nop
.word 0xc004, 0x0000, 0x0000 # 6 byte nop
.popsection
664: TSTMSK \tif_ptr,\tif_mask
jz . + 8
.long 0xb2e8d000
.pushsection .altinstructions, "a"
.long 664b - .
.long 662b - .
.word 82
.byte 12
.byte 12
.popsection
.endm
.macro BPEXIT tif_ptr,tif_mask
TSTMSK \tif_ptr,\tif_mask
.pushsection .altinstr_replacement, "ax"
662: jnz . + 8
.long 0xb2e8d000
.popsection
664: jz . + 8
.long 0xb2e8c000
.pushsection .altinstructions, "a"
.long 664b - .
.long 662b - .
.word 82
.byte 8
.byte 8
.popsection
.endm
.section .kprobes.text, "ax" .section .kprobes.text, "ax"
.Ldummy: .Ldummy:
/* /*
@ -240,9 +275,11 @@ ENTRY(__switch_to)
*/ */
ENTRY(sie64a) ENTRY(sie64a)
stmg %r6,%r14,__SF_GPRS(%r15) # save kernel registers stmg %r6,%r14,__SF_GPRS(%r15) # save kernel registers
lg %r12,__LC_CURRENT
stg %r2,__SF_EMPTY(%r15) # save control block pointer stg %r2,__SF_EMPTY(%r15) # save control block pointer
stg %r3,__SF_EMPTY+8(%r15) # save guest register save area stg %r3,__SF_EMPTY+8(%r15) # save guest register save area
xc __SF_EMPTY+16(8,%r15),__SF_EMPTY+16(%r15) # reason code = 0 xc __SF_EMPTY+16(8,%r15),__SF_EMPTY+16(%r15) # reason code = 0
mvc __SF_EMPTY+24(8,%r15),__TI_flags(%r12) # copy thread flags
TSTMSK __LC_CPU_FLAGS,_CIF_FPU # load guest fp/vx registers ? TSTMSK __LC_CPU_FLAGS,_CIF_FPU # load guest fp/vx registers ?
jno .Lsie_load_guest_gprs jno .Lsie_load_guest_gprs
brasl %r14,load_fpu_regs # load guest fp/vx regs brasl %r14,load_fpu_regs # load guest fp/vx regs
@ -259,11 +296,12 @@ ENTRY(sie64a)
jnz .Lsie_skip jnz .Lsie_skip
TSTMSK __LC_CPU_FLAGS,_CIF_FPU TSTMSK __LC_CPU_FLAGS,_CIF_FPU
jo .Lsie_skip # exit if fp/vx regs changed jo .Lsie_skip # exit if fp/vx regs changed
BPON BPEXIT __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
.Lsie_entry: .Lsie_entry:
sie 0(%r14) sie 0(%r14)
.Lsie_exit: .Lsie_exit:
BPOFF BPOFF
BPENTER __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
.Lsie_skip: .Lsie_skip:
ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE ni __SIE_PROG0C+3(%r14),0xfe # no longer in SIE
lctlg %c1,%c1,__LC_USER_ASCE # load primary asce lctlg %c1,%c1,__LC_USER_ASCE # load primary asce
@ -324,6 +362,7 @@ ENTRY(system_call)
la %r11,STACK_FRAME_OVERHEAD(%r15) # pointer to pt_regs la %r11,STACK_FRAME_OVERHEAD(%r15) # pointer to pt_regs
.Lsysc_vtime: .Lsysc_vtime:
UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER UPDATE_VTIME %r8,%r9,__LC_SYNC_ENTER_TIMER
BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
stmg %r0,%r7,__PT_R0(%r11) stmg %r0,%r7,__PT_R0(%r11)
# clear user controlled register to prevent speculative use # clear user controlled register to prevent speculative use
xgr %r0,%r0 xgr %r0,%r0
@ -362,7 +401,7 @@ ENTRY(system_call)
jnz .Lsysc_work # check for work jnz .Lsysc_work # check for work
TSTMSK __LC_CPU_FLAGS,_CIF_WORK TSTMSK __LC_CPU_FLAGS,_CIF_WORK
jnz .Lsysc_work jnz .Lsysc_work
BPON BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
.Lsysc_restore: .Lsysc_restore:
lg %r14,__LC_VDSO_PER_CPU lg %r14,__LC_VDSO_PER_CPU
lmg %r0,%r10,__PT_R0(%r11) lmg %r0,%r10,__PT_R0(%r11)
@ -597,6 +636,7 @@ ENTRY(pgm_check_handler)
aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE) aghi %r15,-(STACK_FRAME_OVERHEAD + __PT_SIZE)
j 4f j 4f
2: UPDATE_VTIME %r14,%r15,__LC_SYNC_ENTER_TIMER 2: UPDATE_VTIME %r14,%r15,__LC_SYNC_ENTER_TIMER
BPENTER __TI_flags(%r12),_TIF_ISOLATE_BP
lg %r15,__LC_KERNEL_STACK lg %r15,__LC_KERNEL_STACK
lgr %r14,%r12 lgr %r14,%r12
aghi %r14,__TASK_thread # pointer to thread_struct aghi %r14,__TASK_thread # pointer to thread_struct
@ -729,7 +769,7 @@ ENTRY(io_int_handler)
mvc __LC_RETURN_PSW(16),__PT_PSW(%r11) mvc __LC_RETURN_PSW(16),__PT_PSW(%r11)
tm __PT_PSW+1(%r11),0x01 # returning to user ? tm __PT_PSW+1(%r11),0x01 # returning to user ?
jno .Lio_exit_kernel jno .Lio_exit_kernel
BPON BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
.Lio_exit_timer: .Lio_exit_timer:
stpt __LC_EXIT_TIMER stpt __LC_EXIT_TIMER
mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
@ -1165,7 +1205,7 @@ ENTRY(mcck_int_handler)
mvc __LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW mvc __LC_RETURN_MCCK_PSW(16),__PT_PSW(%r11) # move return PSW
tm __LC_RETURN_MCCK_PSW+1,0x01 # returning to user ? tm __LC_RETURN_MCCK_PSW+1,0x01 # returning to user ?
jno 0f jno 0f
BPON BPEXIT __TI_flags(%r12),_TIF_ISOLATE_BP
stpt __LC_EXIT_TIMER stpt __LC_EXIT_TIMER
mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER mvc __VDSO_ECTG_BASE(16,%r14),__LC_EXIT_TIMER
0: lmg %r11,%r15,__PT_R11(%r11) 0: lmg %r11,%r15,__PT_R11(%r11)
@ -1292,7 +1332,8 @@ cleanup_critical:
clg %r9,BASED(.Lsie_crit_mcck_length) clg %r9,BASED(.Lsie_crit_mcck_length)
jh 1f jh 1f
oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST oi __LC_CPU_FLAGS+7, _CIF_MCCK_GUEST
1: lg %r9,__SF_EMPTY(%r15) # get control block pointer 1: BPENTER __SF_EMPTY+24(%r15),(_TIF_ISOLATE_BP|_TIF_ISOLATE_BP_GUEST)
lg %r9,__SF_EMPTY(%r15) # get control block pointer
ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE ni __SIE_PROG0C+3(%r9),0xfe # no longer in SIE
lctlg %c1,%c1,__LC_USER_ASCE # load primary asce lctlg %c1,%c1,__LC_USER_ASCE # load primary asce
larl %r9,sie_exit # skip forward to sie_exit larl %r9,sie_exit # skip forward to sie_exit

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@ -197,3 +197,21 @@ const struct seq_operations cpuinfo_op = {
.stop = c_stop, .stop = c_stop,
.show = show_cpuinfo, .show = show_cpuinfo,
}; };
int s390_isolate_bp(void)
{
if (!test_facility(82))
return -EOPNOTSUPP;
set_thread_flag(TIF_ISOLATE_BP);
return 0;
}
EXPORT_SYMBOL(s390_isolate_bp);
int s390_isolate_bp_guest(void)
{
if (!test_facility(82))
return -EOPNOTSUPP;
set_thread_flag(TIF_ISOLATE_BP_GUEST);
return 0;
}
EXPORT_SYMBOL(s390_isolate_bp_guest);